Conventionally, there has been known a self-propelled electronic device that performs a job such as cleaning, while autonomously traveling on an indoor space or an outdoor space. Such a self-propelled electronic device may be provided with a wheel drop sensor for detecting whether or not a wheel drop condition in which a drive wheel drops off from a floor surface occurs, to prevent the self-propelled electronic device from falling down a downward level difference during autonomous traveling.
The wheel drop sensor detects loss of contact of a drive wheel with a floor surface due to a wheel drop condition in which the drive wheel drops off from the floor surface on a downward level difference. The self-propelled electronic device having an anti-drop function immediately performs an anti-drop operation to prevent a main body from falling down the floor surface, when the wheel drop sensor detects loss of contact of the drive wheel with the floor surface.
Conventionally, as a self-propelled electronic device provided with the wheel drop sensor described above, an invention of a mobile robot cleaner is disclosed in which, when a drop-off of a wheel is detected by the wheel drop sensor, for example, a moving unit is controlled such that the wheel is driven to rotate in the reverse direction for a short time, and then, stops (for example, see Patent Document 1).
In addition, an invention of a self-propelled vacuum cleaner is disclosed which is configured as described below. Specifically, under a condition where loss of contact of a drive wheel with the floor surface is detected by a loss-of-contact detection unit, if a cleaner main body is determined to be close to the floor surface within a predetermined range based on an output from a level difference sensor, the cleaner determines that the drive wheel drops off from a level difference on the floor surface, and tries to escape from the level difference by driving the drive wheel, and if the cleaner main body is determined to be distant from the floor surface beyond the predetermined range based on the output from the level difference sensor, the cleaner determines that the cleaner main body is carried by a user, and stops the drive wheel (for example, see Patent Document 2).